Fan motor

ABSTRACT

A fan motor includes a static body, a rotating body that has a shaft, a hub encircling a first end of the shaft and joined with the first end, and a blade joined around an outer periphery of the hub, a sleeve that retains thereinside a portion of the shaft at a second end side, a rotating flange which encircles the sleeve and which rotates together with the hub, a static flange which is disposed in an area at a side of the first end of the shaft, and which is joined with the static body so as to overlap the rotating flange in a radial direction, a dynamic pressure generating groove provided in either one of surfaces of the static body and the rotating body facing with each other in the axial direction, and a lubricant present between the static body and the rotating body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fan motor including a rotating fanblade.

2. Description of the Related Art

Fan motors that rotate a fan blade are built in electronic devices likea personal computer.

Such fan motors promote heat dissipation inside the electronic device,thereby contributing the downsizing and speedup of such a device.

Fan motors are nowadays often built in especially portable electronicdevices like a laptop computer.

In comparison with the fan motors built in stationary electronic deviceslike a desktop computer, it is necessary for the fan motors built in theportable electronic devices like a laptop computer to have a shockresistance and a vibration resistance in order to withstand a shock likefalling and a vibration at the time of carrying and to have the extendedlifetime.

For example, JP 2007-205491 A discloses a fan motor including a bladefixed to a rotating body and a bearing supporting the rotating body.

Conventional fan motors like one disclosed in JP 2007-205491 A have arotating body with a blade and a static body.

When an acceleration is applied to the blade due to falling, etc., ofthe electronic device, the rotating body with the blade may contact thestatic body in the axial direction.

In general, when the rotating body and the static body contact with eachother, those parts may be damaged in the worst case.

Alternatively, when the rotating body repeats contacting the staticbody, in general, the fan motor breaks down within a relatively shortduration of use, and thus the lifetime thereof becomes short.

Moreover, according to such conventional fan motors, when the bladerotates, the blade receives force in the opposite direction to thedirection of blowing.

When the blade receives such force, the rotating body with the bladetravels in the axial direction, and thus the rotating body and thestatic body may contact with each other.

When the rotating body contacts the static body while the blade isrotating, the contacting portions are worn out, and may be damaged inthe worst case, resulting in the reduction of the lifetime of the fanmotor.

Moreover, when the rotating body contacts the static body while theblade is rotating, slide noises are generated from the fan motor. Suchslide noises are unpleasant to the user of the electronic device.

Such a technical issue arises in the case of fan motors built in othervarious electronic devices in addition to the fan motors built inportable electronic devices.

The present invention has been made in view of the above-explainedcircumstance, and it is an object of the present invention to provide atechnology of preventing a rotating body with a blade from contacting astatic body or suppressing a reduction of the lifetime of a fan motor.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides a fan motor thatincludes: a static body including a base; a rotating body which includesa shaft, a hub encircling a first end of the shaft and joined with thefirst end, and a blade joined around an outer periphery of the hub, andwhich rotates relative to the static body; a sleeve which retainsthereinside a portion of the shaft at a second end side and which isjoined with the base; a rotating flange which encircles at least aportion of the sleeve and which rotates together with the hub; a firststatic flange which is disposed in an area at a side of the first end ofthe shaft in an axial direction and which faces the rotating flange inthe axial direction; a second static flange which is disposed in an areaat a side of the second end of the shaft in the axial direction andwhich faces the rotating flange in the axial direction; a first dynamicpressure generating groove that is provided in either one of surfaces ofthe rotating flange and the first static flange facing with each otherin the axial direction; a second dynamic pressure generating groove thatis provided in either one of surfaces of the rotating flange and thesecond static flange facing with each other in the axial direction; anda lubricant present between the static body and the rotating body.

A second aspect of the present invention provides a fan motor thatincludes: a static body including a base; a rotating body which includesa shaft, a hub encircling a first end of the shaft and joined with thefirst end, and a blade joined around an outer periphery of the hub, andwhich rotates relative to the static body; a sleeve which retainsthereinside a portion of the shaft at a second end side and which isjoined with the base; a rotating flange which encircles at least aportion of the sleeve and which rotates together with the hub; a staticflange which is disposed in an area at a side of the first end of theshaft in an axial direction with reference to the rotating flange andwhich is joined with the static body so as to overlap with the rotatingflange in the radial direction; a dynamic pressure generating groovewhich is disposed outwardly of a portion of the sleeve retaining theshaft in the radial direction and which is provided in either one ofsurfaces of the static body and the rotating body facing with each otherin the axial direction; and a lubricant present between the static bodyand the rotating body.

A third aspect of the present invention provides a fan motor thatincludes: a static body including a base; a rotating body which includesa shaft, a hub encircling a first end of the shaft and joined with thefirst end, and a blade joined around an outer periphery of the hub, andwhich rotates relative to the static body; a sleeve which retainsthereinside a portion of the shaft at a second end side and which isjoined with the base; a rotating flange which encircles at least aportion of the sleeve and which rotates together with the hub; a staticflange which is disposed in an area at a side of the first end of theshaft in an axial direction with reference to the rotating flange, andwhich is joined with the static body so as to overlap the rotatingflange in a radial direction; a dynamic pressure generating grooveprovided in either one of surfaces of the static body and the rotatingbody facing with each other in the axial direction; and a lubricantpresent between the static body and the rotating body.

Any combination of the above-explained structural elements and mutualreplacement of the structural elements and expressions of the presentinvention among a method, a device, and a system, etc., are alsoeffective as an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram showing a fan motor according to an embodiment ofthe present invention;

FIG. 1B is a diagram showing the fan motor according to the embodimentof the present invention;

FIG. 2 is a cross-sectional view taken along a line A-A in FIG. 1A;

FIG. 3 is an enlarged cross-sectional view showing a periphery of ajoined portion between a hub and an annular portion in FIG. 2 in anenlarged manner;

FIG. 4 is an enlarged bottom view showing a periphery of a base hole inFIG. 2 in an enlarged manner; and

FIG. 5 is an enlarged cross-sectional view showing a periphery of arotating flange and a sleeve in FIG. 2 in an enlarged manner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be explained belowwith reference to the accompanying drawings.

The same or equivalent structural element or member shown in respectivefigures will be denoted by the same reference numeral and the duplicatedexplanation thereof will be omitted accordingly.

The dimension of a member in each figure is enlarged or reduced asneeded in order to facilitate understanding.

A part of a member not important to explain the embodiment will be alsoomitted in each figure.

A fan motor of an embodiment is appropriate as a fan motor built in anelectronic device like a personal computer.

Embodiment

FIG. 1A is a top view showing a fan motor 100 according to anembodiment.

FIG. 1B is a side view showing the fan motor 100 of the embodiment.

The fan motor 100 includes a static body 2 and a rotating body 4.

The static body 2 includes a base 6 and an outer periphery wall 16.

The rotating body 4 includes a shaft 8, a hub 10, and a blade unit 12.

The shaft 8 has a first end 8A that is shown in FIG. 1A at a side towarda reader and a second end 8B opposite to the first end 8A.

The explanation below will be given based on a definition that the firstend 8A of the shaft 8 is an upper side with respect to the second end 8Bthereof.

However, the posture of the fan motor of the present invention when inuse is not limited to this definition.

The fan motor of the present invention can be used in any arbitraryposture.

The blade unit 12 includes a blade base 18 and, for example, 10 blades14. The number of blades can be changed as needed depending on theapplication, the rotating speed, etc., of the fan motor 100.

The blade base 18 includes a cylinder part 18A, a disc part 18B, and athrough hole 18C.

The cylinder part 18A is a hollow cylinder.

The disc part 18B protrudes inwardly of the radial direction from theupper end of the cylinder part 18A.

The through hole 18C is disposed at the center of the disc part 18B.

The 10 blades 14 protrude outwardly of the radial direction from theouter periphery of the cylinder part 18A and are fixed thereto.

The blades 14 are disposed at a substantially equal interval in thecircumferential direction.

The blade unit 12 is formed of a resin material like polycarbonate bymolding.

The blade unit 12 may contain glass fibers at a predetermined ratio.

The blade unit 12 has an outer diameter of, for example, 30 mm and aheight of, for example, 5 mm.

The blade unit 12 has the blade base 18 fixed to the hub 10 by bonding.

The blade unit 12 may be fixed to the hub 10 by other techniques.

The outer periphery wall 16 has a substantially rectangular externalshape and an opening 16B located at the center thereof, and encirclesthe blade unit 12.

The outer periphery wall 16 is formed of a resin material likepolycarbonate by molding.

The outer periphery wall 16 may contain glass fibers at a predeterminedratio.

The outer periphery wall 16 has a recess 16A in an end face in the axialdirection.

The base 6 is fitted in the recess 16A of the outer periphery wall 16and fixed to the outer periphery wall 16 by bonding.

FIG. 2 is a cross-sectional view taken along a line A-A in FIG. 1A.

FIG. 2 is symmetrical relative to a rotation axis R.

Hence, indication of a reference numeral to a portion of the sameelement at one side in the horizontal direction will be omitted in FIG.2.

The static body 2 further includes a sleeve 20, a first static flange24, a second static flange 26, a housing 28, a stator core 58, a coreholder 62, coils 60, and a magnetic ring 44.

The rotating body 4 further includes a rotating flange 22.

The rotating flange 22 encircles the sleeve 20, and is fixed to the hub10.

The sleeve 20 encircles the shaft 8.

The sleeve 20 is surrounded by the housing 28 and is fixed thereto.

The housing 28 is fixed to the base 6.

The first static flange 24 is fixed to the sleeve 20, and is locatedabove the rotating flange 22 in the axial direction via a clearance.

The second static flange 26 is fixed to the housing 28, and is locatedbelow the rotating flange 22 in the axial direction via a clearance.

Hence, the rotating flange 22 is rotatable in a space defined by theclearances with the first static flange 24 and with the second staticflange 26 in the axial direction.

The hub 10 includes an external wall 10A, a disc part 10B, a throughhole 10C, and a first cylinder part 36.

The external wall 10A is in a hollow cylindrical shape.

The disc part 10B protrudes inwardly of the radial direction from theupper end of the external wall 10A.

The through hole 10C is provided at the center of the disc part 10B.

The hub 10 is formed of a soft magnetic material like SUS430F.

The hub 10 is formed in a predetermined shape by, for example, cutting.

The hub 10 may be shaped by pressing instead of cutting.

The hub 10 has the external wall 10A fitted inwardly of the cylinderpart 18A of the blade base 18.

The hub 10 has the disc part 10B abutting the lower face of the discpart 10B of the blade base 18.

The hub 10 has the through hole 10C where the first end 8A of the shaft8 is inserted.

The first cylinder part 36 protrudes downwardly from the disc part 10Bin the axial direction.

The first cylinder part 36 has the inner periphery coaxial with thethrough hole 10C.

The first cylinder part 36 encircles and fastens a second cylinder part38 to be discussed later.

FIG. 3 is an enlarged cross-sectional view showing a periphery of ajoined portion between the hub 10 and the blade base 18.

According to the fan motor 100 of this embodiment, the hub 10 has, forexample, six boss holes 10D, and the blade base 18 has, for example, sixbosses 18D.

The six boss holes 10D pass all the way through the disc part 10B in theaxial direction.

The six boss holes 10D are disposed in the circumferential direction ata substantially equal interval.

Conversely, the bosses 18D are provided at positions corresponding torespective boss holes 10D.

The bosses 18D protrude downwardly from the disc part 18B in the axialdirection.

The bosses 18D each include a boss protrusion 18E and a boss thickerpart 18F.

The boss protrusion 18E passes all the way through the boss hole 10D andprotrudes from the lower face of the disc part 10B.

The boss thicker part 18F is fixed to the tip of the boss protrusion18E, and has a larger diameter than that of the boss hole 10D.

The boss thicker part 18F can be formed by heating the tip of the bossprotrusion 18E to let the tip deformed.

That is, the boss 18D, the boss protrusion 18E, and the boss thickerpart 18F are continuous in a seamless manner.

Such a configuration restricts the traveling of the blade base 18 in theaxial direction relative to the hub 10.

Returning to FIG. 2, the rotating flange 22 is in, for example, a flatannular shape.

The rotating flange 22 encircles the sleeve 20, and rotates togetherwith the rotating body 4.

The rotating flange 22 includes a second cylinder part 38 protrudingdownwardly from the outer periphery of the rotating flange 22.

The rotating flange 22 and the second cylinder part 38 are joinedtogether in a seamless manner.

That is, the rotating flange 22 and the second cylinder part 38 are anannular member having a cross section of a reversed L shape.

The rotating flange 22 is formed of an iron-and-steel material likeSUS430F by, for example, cutting.

The rotating flange 22 may be formed of a metal by pressing.Alternatively, the rotating flange 22 may be formed of a resin materialby molding. The rotating flange 22 rotates in a space defined by thefirst static flange 24 and the second static flange 26 in the axialdirection.

The second cylinder part 38 has the outer periphery fixed to the innerperiphery of the first cylinder part 36 by bonding.

A magnet 40 in a ring shape is fixed inwardly of the external wall 10Aof the hub 10 by bonding.

The magnet 40 contains materials, such as neodymium, iron, and born.

The magnet 40 has a surface on which an anti-corrosive process isapplied like electrodeposition coating or spray coating.

The magnet 40 has driving magnetic poles of, for example, 16 polesdisposed in the circumferential direction on the inner periphery of themagnet 40.

The magnet 40 has the inner periphery facing twelve tips 58C of a statorcore 58 to be discussed later in the radial direction.

The shaft 8 is formed of an iron-and-steel material like stainless steelin an elongated cylindrical shape.

The shaft 8 has the first end 8A fitted in the through hole 10C of thehub 10 and fixed thereto by bonding.

The shaft 8 has the second end 8B retained in the sleeve 20 andsupported in a freely rotatable manner.

The sleeve 20 includes a cylinder part 20A.

The cylinder part 20A is a hollow cylinder.

The first static flange 24 extends outwardly of the radial directionfrom the upper part of the cylinder part 20A.

The cylinder part 20A and the first static flange 24 are formed togetherwith each other.

That is, the first static flange 24 is joined with the cylinder part 20Ain a seamless manner.

The first static flange 24 and the cylinder part 20A are formed of ametal like brass by, for example, cutting.

The first static flange 24 and the cylinder part 20A have, for example,an electroless nickel plating layer on the surface thereof.

The first static flange 24 and the cylinder part 20A may be formed of aresin material by molding.

The cylinder part 20A retains the second end 8B of the shaft 8 andsupports the second end 8B in a freely rotatable manner.

The housing 28 includes a cylinder part 28A and a bottom 28C.

The cylinder part 28A is a hollow cylinder.

The second static flange 26 is fixed to an upper end of the cylinderpart 28A.

The bottom 28C is fixed to the lower end face of the cylinder part 28A,and covers the lower end face thereof.

The second static flange 26, the cylinder part 28A, and the bottom 28Care formed together.

That is, the second static flange 26, the cylinder part 28A, and thebottom 28C are joined together in a seamless manner.

The second static flange 26, the cylinder part 28A, and the bottom 28Care formed of a metal like brass by, for example, cutting.

The second static flange 26, the cylinder part 28A, and the bottom 28Chave, for example, electroless nickel plating layer on the surfacethereof. The second static flange 26, the cylinder part 28A, and thebottom 28C may be formed of a resin material by molding.

The outer periphery of the cylinder part 20A of the sleeve 20 is fittedin and bonded with the inner periphery of the cylinder part 28A and thusthe housing 28 fixes the sleeve 20.

That is, the housing 28 has the cylinder part 28A encircling thecylinder part 20A of the sleeve 20.

The second static flange 26 is located below the first static flange 24in the axial direction with a space.

The housing 28 is fitted in a base hole 6A and fixed therewith bybonding.

The base 6 has a substantially rectangular external shape, and has thebase hole 6A passing all the way through in the axial direction at thecenter of the base 6.

The base 6 has ventilation slots in an area facing the blades 14 in theaxial direction.

The base 6 has a core layer mainly composed of, for example, iron, and asurface layer mainly composed of, for example, zinc adhered to thesurface of the core layer.

The base 6 is formed of a cold-rolled steel plate with a zinc plating ina predetermined shape by, for example, pressing.

The base 6 may be formed of the other materials like a stainless steel.

FIG. 4 is a bottom view showing the periphery of the base hole 6A andthe bottom 28C of the housing 28 in an enlarged manner.

The edge of the base hole 6A and the housing 28 have, for example, awelded part 42 joined by welding.

The welded part 42 is in a ring shape along the edge of the base hole6A.

FIG. 5 is an enlarged cross-sectional view showing the periphery of thesleeve 20 in an enlarged manner, and shows the left-half of such aperiphery relative to the rotation axis R.

A pair of radial dynamic pressure generating grooves 50 and 52 aredisposed in the inner periphery of the cylinder part 20A of the sleeve20.

The radial dynamic pressure generating grooves 50 and 52 may be disposedin an outer periphery 8BA of the shaft 8.

The radial dynamic pressure generating grooves 50 and 52 are in, forexample, a herringbone shape.

However, those grooves may be in the other shapes like a spiral shape.

A lubricant 34 is present between the sleeve 20 and the shaft 8.

A first dynamic pressure generating groove 54 is disposed in a surfaceof the rotating flange 22 facing with the first static flange 24 in theaxial direction.

The first dynamic pressure generating groove 54 may be disposed in asurface of the first static flange 24 facing with the rotating flange 22in the axial direction.

A second dynamic pressure generating groove 56 is disposed in a surfaceof the rotating flange 22 facing with the second static flange 26 in theaxial direction.

The second dynamic pressure generating groove 56 may be disposed in asurface of the second static flange 26 facing with the rotating flange22 in the axial direction.

The first and second dynamic pressure generating grooves 54 and 56 areformed in, for example, a herringbone shape.

The first and second dynamic pressure generating grooves 54 and 56 maybe in the other shapes like a spiral shape.

The lubricant 34 is also present between the first static flange 24 andthe rotating flange 22 and between the second static flange 26 and therotating flange 22.

When the shaft 8 and the rotating flange 22 rotate, the radial dynamicpressure generating grooves 50, 52, the first dynamic pressuregenerating groove 54, and the second dynamic pressure generating groove56 respectively generate dynamic pressures applied to the lubricant 34.

A capillary seal 46 is located at a space between the inner periphery ofthe second cylinder part 38 and the outer periphery of the housing 28 inthe radial direction.

The lubricant 34 is continuously present in spaces between the upperface of the bottom 28C of the housing 28 and the sleeve 20 and the shaft8, a space between the first static flange 24 and the rotating flange22, a space between the second static flange 26 and the rotating flange22, and a space between the second cylinder part 38 and the housing 28.

An air-liquid interface 34A of the lubricant 34 contacts both of theinner periphery of the second cylinder part 38 and the outer peripheryof the housing 28 in the capillary seal 46.

The capillary seal 46 has a wide space in the axial direction which isclose to the second end 8B of the shaft 8.

Hence, the capillary seal 46 can suppress a leak-out of the lubricant 34by capillary force.

The static body 2 further has a communicated passage BP of the lubricant34.

The communicated passage BP communicates the capillary seal 46 with aspace above the bottom 28C of the housing 28.

By employing such a structure, the communicated passage BP suppresses apressure difference in the lubricant 34 between the capillary seal 46and the space above the bottom 28C of the housing 28.

The sleeve 20 has a recess 20B formed in the outer periphery of thesleeve 20 and continuous in the direction along the rotation axis R.

The recess 20B is filled with the lubricant 34, and is a part of thecommunicated passage BP.

That is, the communicated passage BP of the lubricant 34 includes therecess 20B.

The housing 28 may have a passage that is a part of the communicatedpassage BP instead of the sleeve 20.

Returning to FIG. 2, the magnetic ring 44 is, for example, a flat ringhaving a through hole provided in the center thereof.

The magnetic ring 44 is formed of, for example, a magnetic steel plateby pressing.

The magnetic ring 44 is located at an area outwardly of the stator core58 in the radial direction.

The magnetic ring 44 faces a lower end face 40A of the magnet 40 in theaxial direction, and is fixed to the base 6 by bonding.

The magnetic ring 44 may be fixed to the base 6 by caulking.

The magnetic ring 44 causes the magnet 40 to have magnetic suction forcein the direction toward the base 6.

As a result, the blades 14 are pushed down in the direction toward thebase 6, and it becomes possible to prevent the blades 14 from floatingbecause of reactive force of airflows produced by the blades 14.

The magnetic ring 44 may be joined together with the base 6 in aseamless manner.

The stator core 58 includes a core annular part 58A, for example, twelvecore teeth 58B and a core tip 58C.

The core annular part 58A is in a ring shape surrounding the centerhole.

The twelve core teeth 58B protrude outwardly of the radial directionfrom the outer periphery of the core annular part 58A.

The twelve core teeth 58B are arranged at, for example, substantiallyequal interval in the circumferential direction.

The core tip 58C extends outwardly of the radial direction at respectiveouter peripheries of the core teeth 58B.

The stator core 58 is fixed to an upper face of the base 6 by means of acore holder 62 to be discussed later.

The stator core 58 is formed by stacking and caulking, for example, sixthin electromagnetic steel plates together.

The core teeth 58B are surrounded by a cover 62C to be discussed later.

The stator core 58 may have an insulative layer formed on the surfacethereof.

Such an insulative layer is formed by, for example, electrodepositioncoating, or powder coating.

The coil 60 is provided at each of the core teeth 58B of the stator core58.

The coil 60 is formed by winding, for example, an electrical wirecovered with an insulative material like poly urethane around each ofthe core teeth 58B.

The coil 60 is coupled to a predetermined drive circuit.

When a drive current of a three-phase substantially sinusoidal wave iscaused to flow through the coil 60, drive magnetic fluxes are generatedalong the core tip 58C.

The core holder 62 includes a mount 62A, a cover 62C, and for example,six spacers 62D.

The mount 62A joins the cover 62C and the six spacers 62D in a seamlessmanner.

The mount 62A, the cover 62C, and the six spacers 62D may be formedseparately and joined together later.

The core holder 62 is formed of a resin material like poly-carbonate bymolding.

The core holder 62 may contain glass fibers, etc., at a predeterminedratio.

The mount 62A is formed in, for example, a substantially annular shape.

The mount 62A may be in other shapes.

The mount 62A surrounds the housing 28.

The mount 62A is present between the core annular part 58A and the base6 in the axial direction.

The spacer 62D is present between the core tip 58C and the base 6 in theaxial direction.

The six spacers 62D are each in a substantially cylindrical shape, anddisposed in the circumferential direction at a substantially equalinterval.

The spacer 62D has a protrusion 62E and a stopper 62F.

The core teeth 58B is fastened to the cover 62C, thereby fastening thestator core 58 to the core holder 62.

The base 6 has a holder hole 6B at a location corresponding to each ofthe spacers 62D.

The holder hole 6B passes all the way through the base 6 in the axialdirection, and includes a smaller diameter part and a larger diameterpart successive from the lower portion of the smaller diameter part.

The spacer 62D has the protrusion 62E passing all the way through theholder hole 6B.

The stopper 62F is retained in the larger diameter part of the holderhole 6B, and has a larger diameter than the minimum diameter of theholder hole 6B.

The stopper 62F can be formed by heating the protrusion 62E to bedeformed.

According to such a structure, the stator core 58 and the core holder 62are fixed to the base 6.

Next, an explanation will be given of an operation of the fan motor 100employing the above-explained structure together with an advantagethereof.

In order to rotate the blades 14, a drive current of a three-phasesubstantially sinusoidal wave is supplied from the predetermined drivecircuit to the coils 60.

As a result, the drive magnetic fluxes are generated along the core tip58C.

Such magnetic fluxes give a torque to the magnet 40, and the blades 14and the hub 10 fastened to the magnet 40 start rotating by that torque.

For example, the blades 14 generate airflows downwardly of the axialdirection by their own rotation.

The blades 14 may generate airflows upwardly of the axial direction bytheir own rotation.

When the hub 10 starts rotating, the joined portion between the hub 10and the blade base 18 receives force in the direction of rotation.Hence, when the hub 10 repeats rotating and stopping inherent to the useof the fan motor 100, the force in the direction of rotation maymutually displace the hub 10 and the blade base 18, and such a joinedportion may be damaged.

However, according to the fan motor 100 of this embodiment, the hub 10has the six boss holes 10D and the blade base 18 has the six bosses 18D.

Since each boss 18D passes all the way through each boss hole 10D, themutual displacement of the blade base 18 to the hub 10 in the directionof rotation can be restricted.

Accordingly, even if the force in the direction of rotation is appliedto the joined portion between the hub 10 and the blade base 18, the hub10 and the blade base 18 are fastened together and are capable ofwithstanding such a force. Hence, the possibility that the joinedportion is damaged can be reduced.

When the shaft 8 and the rotating flange 22 rotate, the radial dynamicpressure generating grooves 50, 52, and the first and second dynamicpressure generating grooves 54, 56 respectively generate dynamicpressures applied to the lubricant 34, and such dynamic pressuressupport the rotating body 4 with the blades 14 in the radial directionand in the axial direction.

In general, when the diameter of a dynamic pressure generating groove isreduced, the dynamic pressure to be generated becomes small. This bringsabout the reduction of the rigidity of a bearing, and the possibilitythat the rotating body and the static body contact increases.

According to the fan motor 100 of this embodiment, the rotating flange22 is located outwardly of the radial direction from the cylinder part20A of the sleeve 20.

Hence, the first and second dynamic pressure generating grooves 54 and56 are located outwardly of the shaft 8 or the cylinder part 20A of thesleeve 20 in the radial direction.

Accordingly, respective diameters of the first and second dynamicpressure generating grooves 54, 56 can be increased. As a result, thedynamic pressure to be generated is increased to support the rotatingbody 4 with the blades 14 in the radial direction and in the axialdirection in a non-contact manner with the static body 2, and toincrease the rigidity of the bearing. Moreover, the non-contactcondition results in a suppression of the generation of slide noises.

Moreover, in the rotating operation, the blades 14 may receive anacceleration in a direction departing from the base 6 in the axialdirection. In this case, the rotating body 4 with the blades 14 may movein the direction departing from the base 6 in the axial direction, andrespective faces of the static body 2 and the rotating body 4 facingwith each other in the axial direction may contact with each other. Inthe worst case, the fan motor 100 breaks down if such a contact repeats.

According to the fan motor 100 of this embodiment, however, the firstand second dynamic pressure generating grooves 54 and 56 are provided inboth faces of the rotating flange 22 in the axial direction.

As explained above, the first and second dynamic pressure generatinggrooves 54 and 56 support the rotating body 4 with the blades 14 in anon-contact manner with the static body 2 in the axial direction at thetime of the rotating operation, and thus the possibility that therotating body 4 contacts the static body 2 can be reduced.

It is presumed that an end of the shaft 8 where the rotating body 4 withthe blades 14 is joined is an output end of the shaft 8. In this case,according to the fan motor 100 of this embodiment, the first end 8A isthe output end.

According to a design of disposing a dynamic pressure generating grooveat an area distant from the output end of the shaft in the axialdirection, the shaft has a high possibility of precessing when rotating.

When the shaft precesses, the wear of the shaft or the sleeve mayincrease, resulting in the reduction of the lifetime of the fan motor.

However, according to the fan motor 100 of this embodiment, the rotatingflange 22 is disposed at an area close to the first end 8A of the shaft8 rather than the second end 8B thereof in the axial direction.

Hence, the first and second dynamic pressure generating grooves 54 and56 are located at respective areas close to the first end 8A of theshaft 8 rather than the second end 8B thereof in the axial direction.

As a result, the possibility that the shaft 8 precesses can be reduced,thereby suppressing the reduction of the lifetime of the fan motor 100.

In addition, according to the fan motor 100 of this embodiment, therotating flange 22 is located at an area close to the first end 8A ofthe shaft 8 rather than the weighted center G of the rotating body 4 inthe axial direction.

Since the rotating flange 22 is distant from the second end 8B of theshaft 8, the principle of leverage acts, and the rotating flange 22together with the first and second static flanges 24 and 26 can suppressthe precession movement of the shaft 8, i.e., the wobbling of therotating body 4 in the rotational direction.

According to such a configuration, the rotating flange 22 can support,together with the first and second static flanges 24 and 26, anoff-centered load by contacting one another when the fan motor 100 isnot rotating and when the off-centered load is applied to the blades 14.

When the fan motor has a dimension in the axial direction constant andthe rotating flange is fixed to the shaft, the dimension of the radialdynamic pressure generating groove in the axial direction decreases bywhat corresponds to such a configuration, resulting in the reduction ofthe bearing rigidity in some cases.

However, according to the fan motor 100 of this embodiment, the rotatingflange 22 is fixed to the hub 10, and thus it does not bring about thereduction of the bearing rigidity.

The embodiment of the present invention was explained above, but thepresent invention is not limited to the above-explained embodiment.Various changes and modifications can be made without departing from thescope and spirit of the present invention.

What is claimed is:
 1. A fan motor comprising: a static body including abase; a rotating body which includes a shaft, a hub encircling a firstend of the shaft and joined with the first end, and a blade joinedaround an outer periphery of the hub, and which rotates relative to thestatic body; a sleeve which retains thereinside a portion of the shaftat a second end side and which is joined with the base; a rotatingflange which encircles at least a portion of the sleeve and whichrotates together with the hub; a first static flange which is disposedin an area at a side of the first end of the shaft in an axial directionand which faces the rotating flange in the axial direction; a secondstatic flange which is disposed in an area at a side of the second endof the shaft in the axial direction and which faces the rotating flangein the axial direction; a first dynamic pressure generating groove thatis provided in either one of surfaces of the rotating flange and thefirst static flange facing with each other in the axial direction; asecond dynamic pressure generating groove that is provided in either oneof surfaces of the rotating flange and the second static flange facingwith each other in the axial direction; and a lubricant present betweenthe static body and the rotating body.
 2. The fan motor according toclaim 1, wherein the rotating flange is located outwardly of a portionof the sleeve retaining the shaft in a radial direction.
 3. The fanmotor according to claim 1, wherein the rotating flange is located at anarea close to the first end of the shaft rather than the second endthereof in the axial direction.
 4. The fan motor according to claim 1,wherein the rotating flange is located in an area at the side of thefirst end of the shaft beyond a weighted center of the rotating body inthe axial direction.
 5. The fan motor according to claim 1, wherein therotating flange is joined with the hub.
 6. The fan motor according toclaim 1, wherein the first static flange is joined with the sleeve. 7.The fan motor according to claim 1, further comprising a radial dynamicpressure groove provided in either one of an outer periphery of theshaft and an inner periphery of the sleeve.
 8. The fan motor accordingto claim 1, further comprising a housing which is joined with the secondstatic flange and which encircles the sleeve.
 9. The fan motor accordingto claim 8, wherein the base is provided with a base hole where thehousing is inserted to fasten the housing, and the fan motor furthercomprising a welded part that joins an edge of the base hole with thehousing.
 10. The fan motor according to claim 1, further comprising: amagnet joined with the hub; and a magnetic member which is joined withthe static body and which suctions the magnet toward the base.
 11. Thefan motor according to claim 1, further comprising: a first cylinderpart joined with the hub; and a second cylinder part encircled by andjoined with the first cylinder part and having an inner peripheryholding an air-liquid interface of the lubricant.
 12. The fan motoraccording to claim 11, wherein the second cylinder part and the rotatingflange are joined together in a seamless manner.
 13. The fan motoraccording to claim 1, further comprising: a stator core including a coreencircling part, core teeth running outwardly of the radial directionfrom the core encircling part and each having a coil, and a core tiprunning outwardly of the radial direction from the core teeth; a coreholder that joins the stator core and the base; and a ring magnet whichencircles the stator core, is joined with the hub, and has a magneticpolarity at a surface facing the core tip in the radial direction. 14.The fan motor according to claim 13, further comprising a spacer presentbetween the core tip and the base in the axial direction.
 15. A fanmotor comprising: a static body including a base; a rotating body whichincludes a shaft, a hub encircling a first end of the shaft and joinedwith the first end, and a blade joined around an outer periphery of thehub, and which rotates relative to the static body; a sleeve whichretains thereinside a portion of the shaft at a second end side andwhich is joined with the base; a rotating flange which encircles atleast a portion of the sleeve and which rotates together with the hub; astatic flange which is disposed in an area at a side of the first end ofthe shaft in an axial direction with reference to the rotating flangeand which is joined with the static body so as to overlap with therotating flange in the radial direction; a dynamic pressure generatinggroove which is disposed outwardly of a portion of the sleeve retainingthe shaft in the radial direction and which is provided in either one ofsurfaces of the static body and the rotating body facing with each otherin the axial direction; and a lubricant present between the static bodyand the rotating body.
 16. The fan motor according to claim 15, whereinthe rotating flange is located outwardly of a portion of the sleeveretaining the shaft in a radial direction.
 17. The fan motor accordingto claim 15, wherein the rotating flange is located at an area close tothe first end of the shaft rather than the second end thereof in theaxial direction.
 18. The fan motor according to claim 15, wherein therotating flange is located in an area at the side of the first end ofthe shaft beyond a weighted center of the rotating body in the axialdirection.
 19. The fan motor according to claim 15, wherein the staticflange is joined with the sleeve.
 20. A fan motor comprising: a staticbody including a base; a rotating body which includes a shaft, a hubencircling a first end of the shaft and joined with the first end, and ablade joined around an outer periphery of the hub, and which rotatesrelative to the static body; a sleeve which retains thereinside aportion of the shaft at a second end side and which is joined with thebase; a rotating flange which encircles at least a portion of the sleeveand which rotates together with the hub; a static flange which isdisposed in an area at a side of the first end of the shaft in an axialdirection with reference to the rotating flange, and which is joinedwith the static body so as to overlap the rotating flange in a radialdirection; a dynamic pressure generating groove provided in either oneof surfaces of the static body and the rotating body facing with eachother in the axial direction; and a lubricant present between the staticbody and the rotating body.